Topological amplitudes in heterotic strings with Wilson lines

Abstract

We consider d=4, N = 2 compactifications of heterotic strings with an ar- bitrary number of Wilson lines. In particular, we focus on known chains of candidate heterotic/type II duals. We give closed expressions for the topological amplitudes F (g) in terms of automorphic forms of SO(2+k, 2, Z), and find agreement with the geometric data of the dual K3 fibrations wherever those are known.